Relay flip-flop



March 19, 1968 R. c. SWANSON 3,374,401

RELAY FLIP-FLOP Filed May 15, 1965 v a b C d a b 0 d CL CLOSED NPUT CONTACT PR. I? v UWUUUHJC TRANSFER -CLOSED swlTC I CONTACT PRIB OPEN OPERATED RELAY H j RE| EAsED OPERATED REL L-RELEA$ED TIME FIG. 2

INVENTOR ROBERT C. SWANSON ATTORN Y United States Patent C 3,374,401 RELAY FLIP-FLOP Robert C. Swanson, Chicago, Ill., assignor to Teletype Corporation, Skokie, 11]., a corporation of Delaware Filed May 13, 1965, Ser. No. 455,514 7 Claims. (Cl. 317-140) ABSTRACT OF THE DISCLOSURE A relay flip-flop of the type wherein successive operations of an input switch cause a first relay to be operated, a second relay to be operated, the first relay to be disabled and the second relay to be disabled characterized in that operation of the relays establishes alternative holding paths for the relays through the contacts of the input switch so that later operations of the switch disable the relays by opening their holding paths.

This invention relates to relay flip-flop circuits and more particularly to circuits of the type commonly known as frequency dividers.

Frequency divider flip-flops, so called because they produce one output signal for each two input signals and accordingly can be used to produce an output having a frequency equal to one-half the input frequency, often employ two self-locking relays which are alternately energized and deenergized by successive actuations of the input device. Usually one contact pair of each of the relays is used to set up a deenergizing path for the other of the relays, these paths being simply a shunting resistance in series with the coil of the relay. Relay fiipfiops of this type are inherently slow operating because, since the time constant of an inductive circuit is equal to the inductance of the circuit divided by the resistance of the circuit, the slowest way to deenergize a relay is to place a shunt across its coil.

Accordingly, an object of this invention is to provide a fast operating relay fiipflop.

Another object of this invention is to provide a relay flip-flop which is deenergized by placing an infinite resistance in series with the coils of its relays when it is desired to deenergize the relays.

According to the preferred embodiment of the invention these and other objects are achieved by providing a pair of relays one of which has two transfer contacts and the other of which has two make contacts. The relays are connected to a pulsing transfer contact input switch in a circuit arrangement wherein successive, alternative engagements of the pulsing transfer contact with each of its associated contacts will alternately effect the closing and opening of energizing circuits for the relays.

A further understanding of the invention may be had by referring to the following detailed description when taken in conjunction with the drawings wherein:

FIG. 1 is a schematicillustration of a relay flip-flop circuit employing the present invention, and

FIG. 2 is a timing diagram showing the sequence of operation of the various components of the circuit shown in FIG. 1 through two complete cycles of operation.

Referring now to the drawings wherein like reference numerals represent like parts in each of the views, with particular reference being had to FIG. 1 there will be seen a relay flip-flop circuit 10 which is comprised of a first relay 11, a second relay 12 and an input transfer switch 13 which is of the make-before-break variety. In FIG. 2 there is shown a timing diagram in which the operations of these three components are plotted with respect to time. The time divisions of the diagram shown in FIG. 2 are pictured as being of equal length. It should Patented Mar. 19, 1968 be understood, however, that the time intervals between the different operations of the device may be of any desired length, and need not necessarily be equal.

During the time interval between time points represented by the vertical lines a and b of FIG. 2, that is, during the initial phase of the operation of a device, both of the relays 11 and 12 are deenergized and a first contact pair 17 of the input transfer switch 13 is closed. When the point in time indicated by the vertical line b is reached the input transfer switch 13 is operated and the second contact pair 18 of the switch 13 is closed. This operation opens the first contact pair 17 of the switch 13 and also completes an operating circuit for the first relay 11 from ground through the contact pair 18 of the switch 13, a lead 20, a normally closed contact pair 21 of the second relay 12, a lead 22, a lead 23 and the coil of the relay 11 to a power source 24. This causes the relay 11 to operate and when it does the relay 11 closes a normally open contact pair 30 thus completing a holding path for itself from the power source 24 through the coil of the relay 11, the lead 23, a lead 31, the normally open, now closed, contact pair30, a lead 32 and a normally closed contact pair 33 of the relay 12 to ground. Operation of the relay 11 also closes a normally open contact pair 37 which sets up an operating path for the relay 12.

When the point in time indicated by the vertical line c in FIG. 2 is reached the input transfer switch 13 is moved to close its first contact pair 17 and to open its second contact pair 18. This operation connects an operating path for the second relay 12 from ground through the contact pair 17 of the switch 13, a lead 38, a diode 51, the normally open, now closed contact pair 37 of the relay 11, a lead 39, a lead 40 and the coil of the relay 12 to the power source 24. This causes the relay 12 to operate and when it does, the relay 12 transfers the holding circuit for the relay 11 from the path including the normally closed contact pair 33 of the relay 12 to a path including a normally open, now closed contact pair 45 of the relay 12, a lead 46 and the first contact pair 17 of the input transfer switch 13. Thus the holding of the relay 11 is now dependent upon the remaining closed of the first contact pair 17 of the switch 13. It should be noted that, since the contact pairs 33 and 45 are make-before-break contacts, the transfer of the holding circuit for the relay 11 from the contact pair 33 to the contact pair 45 does not result in even a momentary loss of a holding path for the relay 11.

Operation of relay 12 also opens the normally closed contact pair 21 and closes a normally open contact pair 50. In so doing the relay 12 sets up. a hold path for itself through either contact pair 17 or 18 of the input transfer switch 13. When the point in time indicated by the line d in FIG. 2 is reached, the input transfer switch 13 again operates. This transfers the holding path for the relay 12 to a path from ground through the contact pair 18, the lead 20, the normally open, now closed contact pair 50, the lead 39 and the lead 40 to the coil of the relay 12 and to the power source 24. It should be noted that since the input transfer switch 13 is of the make-before-break variety the transfer of the holding circuit for the relay 12 from the circuit including the contact pair 17 to the circuit including the contact pair 18 is accomplished without the occurrence of a period of time during which no holding path is available for the relay 12.

After the contact 17 of the input transfer switch 13 is opened, the holding path for the first relay 11 is broken and consequently, this relay deenergizes. A diode 51 is provided in the lead 38 for preventing a holding path from being established for the relay 11 from ground through the contact pair 18 of the switch 13, the lead 20, the normally open, now closed contact pair 56 of the relay 12, the lead 39, the normally open, now closed contact pair 37 of the relay 11, the lead 38, the lead 46, the normally open, now closed contact pair 45 of the relay 12, the lead 32, the normally open, now closed contact pair 36 of the relay 11, the lead 31, the lead 23, and the coil of the relay 11 to the power source 24. Additionally, since the relay 12 is being held operated a holding path cannot be established for the relay 11 through the normally closed, now open contact pair 33 of the relay 12. Thus, since all the holding paths are broken the relay 11 will deenergize. This will open the contact pair 37 thereby eliminating the holding path for the relay 12 through the first contact pair 17 of the input transfer switch 13.

When the point in time indicated by the vertical line a is reached, the input transfer switch 13 is again moved to open its second contact pair 18 and to close its first contact pair 17. When the second contact pair 18, of input transfer switch 13, is opened it will open the holding path for relay 12 from ground through the now open contact pair 18, lead 20, the normally open now closed contact pair 50 of relay 12, lead 40, and the coil of relay 12 to the power source 24. Since the relay 11 is deenergized the contact pair 37 will be open and accordingly, the holding path for the relay 12 through the contact 37 and the leads 38 and 39 will be open. Thus, the closing of the contact pair 17' and the opening of contact pair 18 breaks all of the holding paths for the relay 12. The relay 12 will, therefore, deenergize and the circuit will be returned to its start position with both relays deenergized and the switch 17 closed. Upon a reactuation of the input transfer switch 18 the cycle will be reinitiated as is indicated by the rightward half of the timing diagram shown in FIG. 2.

It should be understood that the operations of the input transfer switch 13 may be controlled by any suitable means, such as a relay. It should further be understood that suitable contacts may be added to the relay 11 and/ or the relay 12 to provide the desired output for the device. As is indicated by the timing diagram shown in FIG. 2, if a normally open and a normally closed contact pair are added to each of the relays 11 and 12, an output will be obtainable which has exactly one-half the frequency of the input signal which is controlling the operation of the switch 13 and which has any of the four possible phase relationships to the input signal. Accordingly, by adding suitable contacts to the relays 11 and 12, the above described circuit may be operated as a frequency divider.

Although only one embodiment of the invention is shown in the drawings and described in the foregoing specification, it will be understood that invention is not limited to the specific embodiment described, but is capable of modification and rearrangement and substitution of parts and elements without departing from the spirit of the invention.

What is claimed is:

1. A frequency divider circuit comprising:

a pair of relays;

an input transfer switch having a transfer contact and two stationary contactswhich comprise two contact airs;

means operable upon a first closing of a first contact pair of the input switch for energizing a first of the relays;

means operable after the energization of the first relay for holding the first relay energized;

means operable upon a first closing of the second con- .tact pair of the input switch for energizing a second of the relays;

means operable after energization of the second of the relays for holding the first relay energized;

means operable upon a second closing of the first contact of the input switch for breaking the holding means for the first relay and for establishing a holding circuit for the second relay, and

means operable upon a second closing of the second 4 contact pair of the energizing switch for breaking the holding circuit for the second relay.

2. A relay flip-flop circuit comprising:

a pair of relays;

a source of potential;

means including a first contact pair of one of the relays for energizing the other of the relays from the source of potential;

means including a second contact pair of said one of the relays and a first contact pair of said other of the relays for holding said other of the relays energized;

means including a second contact pair of said other of the relays for energizing said one of the relays and for holding said one of the relays energized;

alternate means including a third Contact pair of said one of the relays for holding said one of the relays energized and for disabling the energizing circuit of said other of the relays, and

means for disabling said alternate holding circuit for said one of the relays.

3. A relay flip-flop circuit comprising:

an energizing transfer switch having a transfer contact and two stationary contacts, the transfer contact and a first of the stationary contacts comprising a first contact pair and the transfer contact and the other stationary contact comprising a second contact pair;

a pair of relays;

means including the first contact pair of the energizing switch and a first contact pair of a first of the relays for connecting a source of potential to a second of the relays thereby energizing the second of the relays;

means including the second contact pair of the energizing switch, a second contact pair of the first of the relays and a first contact pair of the second of the relays for connecting a source of potential to the second of the relays thereby holding the second of the relays energized;

means including the second contact pair of the energizing switch and a second contact pair of the second relay for connecting a source of potential to the first of the relays thereby energizing and holding energized the first of the relays;

means for disabling the holding means for the second of the relays;

means for preventing a holding circuit for the second of the relays from being established through the first contact pair of the energizing switch, a third contact pair of the first of the relays, the second contact pair of the second of the relays, the first contact pair of the second of the relays and the second contact pair of the first of the relays, and

means for breaking the second alternative holding circuit for the second of the relays.

4. A relay flip-flop circuit comprising:

an energizing transfer switch having first and second contact pairs each comprising a stationary contact and the same transfer contact;

a pair of relays;

a source of potential for selective connection to the coils of the relays;

means including the first contact pair of the energizing switch, a first contact pair of a first of the relays and the source of potential for energizing a second of the relays;

means including a first contact pair of the second of the relays, a second contact pair of the first of the relays and the source of potential for holding the sec- 0nd of the relays energized;

Alternative means including the second contact pair of the energizing switch, a third contact pair of the first of the relays, a second contact pair of the second of the relays and the source of potential for holding the second of the relays energized;

means including the second contact pair of the energizing switch, the second contact pair of the second relay and the source of potential for energizing and for holding energized the first of the relays;

alternative means including the first contact pair of the energizing switch, a fourth contact pair of the first relay and the source of potential for holding the first relay energized; and

means for disabling the alternative holding means for the second of the relays and for disabling the alternative holding means for the first of the relays.

5. A relay flip-flop circuit comprising:

an input transfer switch having a transfer contact and two stationary contacts which comprise two contact pairs;

a first relay having two contact pairs and operable upon energization to close both contact pairs;

at second relay having four contact pairs and operable upon energization to close two of the contact pairs and to open the remaining two contact pairs;

an energizing circuit including a first contact pair of the input switch, a first lead and a first, normally closed contact pair of the second relay for operation upon a first closure of the first contact pair of the input switch to energize the first relay;

a holding path including a second, normally closed, contact pair of the second relay, a second lead and a first, normally open contact pair of the first relay for holding the first relay operated;

an energizing path including the second contact pair of the input switch, a third lead, a second, normally open contact pair of the first relay and a fourth lead for operation upon a first closing of the second contact pair of the input switch to energize the second relay;

an alternative holding path including the second contact pair of the input switch, a fifth lead, a third, normally open, contact pair of the second relay, the second lead and the first, normally open contact pair of the first relay for holding the first relay energized after the actuation of the second relay;

a holding path for the second relay including the first contact pair of the input switch, the first lead and a fourth, normally open contact pair of the second relay for operation upon a second closure of the first contact pair of the input switch to hold the second relay energized, said closure of the input switch also opening the second contact pair of the input switch thereby breaking the alternative holding path for the first relay;

a diode in the third lead for preventing a holding path for the first relay from being established through the first contact pair of the input switch, the first lead, the fourth, normally open contact pair of the second relay, the fourth lead, the second, normally open contact pair of the first relay, the third lead, the fifth lead, the third, normally open contact pair of the second relay, the second lead and the first normally open contact pair of the first relay;

said input transfer switch being operable upon a second closure of the second contact pair to open the holding circuit for the second relay thereby leaving both the first and the second relay deenergized.

6. A relay flip-flop circuit including:

a pair of relays;

an input switch having two contact pairs;

means responsive to a first closing of a first contact pair of the input switch for energizing a first of the relays;

means responsive to a first closing of a second contact pair of the input switch for energizing a second of the relays;

means responsive to the energization of the second of the relays for establishing a holding circuit for the first of the relays through the second contact pair of the input switch so that upon a second closing of the first contact pair of the input switch the holding circuit for the first relay is opened and the first relay is thereby deenergized; and

means responsive to the deenergization of the first relay for establishing a holding circuit for the second relay through the first contact pair of the input switch so that upon a second closing of the second contact pair of the input switch the holding circuit for the second of the relays is opened and the second of the relays is thereby deenergized.

7. A relay flip-flop circuit including:

a pair of relays;

an input switch having two contact pairs;

means responsive to a first closing of a first contact pair of the input switch for energizing the first of V the relays;

means responsive to a first closing of a second contact pair of the input switch for energizing the second of the relays;

means responsive to the energization of the second of the relays for establishing a holding circuit for the first of the relays;

means responsive to a second closing of the first contact pair of the input switch for opening the holding circuit for the first relay there-by deenergizing the relay;

means responsive to the deenergization of the first of the relays for establishing a holding circuit for the second of the relays; and

means responsive to a second closing of the second contact pair of the input switch for opening the holding circuit for the second of the relays thereby deenergizing the relay.

References Cited UNITED STATES PATENTS 3,275,896 9/1966 Deeg 317-155 X 3,025,433 3/1962 Rogers 317- 2,814,003 11/1957 Alizon 317-140 2,561,073 7/1951 Schouten et al 317140 MILTON O. HIRSHFIELD, Primary Examiner J. A. SILVERMAN, Assistant Examiner. 

